Characteristics of type III radio bursts and solar S bursts

TL;DR

This study analyzes the spectral characteristics of solar S bursts and Type III radio bursts using LOFAR observations, revealing differences in their bandwidths, durations, and drift rates, and confirming their plasma emission origin.

Contribution

It provides detailed observational analysis of solar S bursts and Type III bursts, highlighting their spectral differences and confirming their emission mechanisms.

Findings

S bursts have narrower bandwidths and shorter durations.

S bursts exhibit about half the drift rate of Type III bursts.

Both burst types originate from plasma emission regions in the corona.

Abstract

The Sun is an active source of radio emission which is often associated with the acceleration of electrons arising from processes such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), numerous solar S bursts (where S stands for short) and storms of Type III radio bursts have been observed, that are not directly relates to flares and CMEs. Here, we expand our understanding on the spectral characteristic of these two different types of radio bursts based on observations from the Low Frequency Array (LOFAR). On 9 July 2013, over 3000 solar S bursts accompanied by over 800 Type III radio bursts were observed over a time period of ~8 hours. The characteristics of Type III radio bursts are consistent to previous studies, while S bursts show narrow bandwidths, durations and drift rates of about 1/2 the drift rate of Type III bursts. Type III bursts and solar S bursts occur in a region in the corona where plasma emission is the dominant emission mechanism as determined by data constrained density and magnetic field models.